Corymorpha rubicincta, a new Hydroid (Hydrozoa, Anthoathecata, Corymorphidae) from Port Phillip, Australia Author Watson, Jeanette E. text Memoirs of Museum Victoria 2008 2008-12-31 65 185 188 https://museumsvictoria.com.au/collections-research/journals/memoirs-of-museum-victoria/volume-65-2008/pages-185-188/ journal article 10.24199/j.mmv.2008.65.11 1447-2554 12211185 Corymorpha M. Sars, 1835 Diagnosis (after Brinckman-Voss (1970) , Petersen (1990) and Bouillon et al (2006) . Hydroid solitary, hydranth vasiform with one or several closely set whorls of oral filiform tentacles and aboral whorl of filiform tentacles; hydrocaulus with thin perisarc, with longitudinal peripheral canals; lower part with papillae and/or long anchoring filaments; parenchymatic diaphragm; gonophores borne on blastostyles just above aboral tentacles giving rise to free medusa or fixed sporosacs. Material examined. Holotype NMVF147476 , one stem alcohol preserved, coll: J.E. Watson , 5 June 2008 . Paratypes , NMVF 147477 , six stems alcohol preserved, coll: J.E. Watson , 18 June 2002 . NMVF147478 , six stems coll: J.E. Watson , 5 June 2008 . All material collected from 4.5 -6 m depth. Material initially hardened in 5% formalin then transferred to alcohol. Description (from live and preserved) holotype and paratypes Hydroids solitary,hydrocaulus up to 4cm high,base of hydrocaulus blunt, embedded in sediment and rooted by a thick mass of soft, intergrown hair-like filaments adherent to sand grains; filaments slightly thicker near point of attachment to hydrocaulus. Hydrocaulus cylindrical, widest at base, tapering gradually to a transverse red band about one third to half distance up stem; stem then of same diameter to base of hydranth. Perisarc above band thin and becoming almost colourless distally; a constriction at base of hydranth; in some stems a second red band at constriction marking junction of stem with hydranth. Cauline perisarc below primary band thick and gelatinous with numerous digitate pendulous papillae; papillae becoming shorter with distance up stem, gradually reducing to wavy discontinuous internal lines of cream-coloured spots sometimes interspersed with red blotches. Hydranth long, vasiform, capable of great extension and contraction with a single whorl of 20-24 long, slender filiform aboral tentacles tapering to a pointed tip; approximately 30 oral tentacles, much shorter than aborals, arranged in a tuft of two closely set rows, tentacles in each row alternating with those above and below. Hypostome conical when closed and oral tentacles tightly bunched, when hypostome widely open, tentacles arched backwards. Gonophores fixed sporosacs, borne on blastostyles set in one whorl just above aboral tentacles, a blastostyle usually between each second or third tentacle.Blastostyle short, stout, unbranched, straight to backwardly recurved; up to 20 small subspherical to knuckle-shaped gonophores clustered in groups of three to five without peduncle along one side; gonophores probably cryptomedusoid with a thick epidermal layer heavily armed with nematocysts; more mature sporosacs packed with small ova. Colour: rooting filaments colourless to greenish; lower two thirds of hydrocaulus yellow to reddish, colour gradually fading distally to primary band; primary band brick red; papillae below band cream.Body of hydranth pale flesh-colour, hypostome white to cream, usually a band of red spots just above aboral tentacles and similar spots on bases of inner row of oral tentacles; blastostyle and gonophores colourless to white. Tentacles translucent white. Measurements (mm) of hydrocaulus from live specimens

Hydrocaulus
length overall	20 – 40
diameter at base	2 – 3
diameter at cauline band	2.2 – 2.5
diameter below hydranth	1.5 – 2
distance from red cauline band to base of hydranth	5 – 12
Hydranth
diameter at constriction below aboral tentacles 1.5 – 2
length of oral tentacle	3.8 – 4.5
length of aboral tentacle	12 – 14
Blastostyle (immature)
length	0.1 – 1.5

Figure 2. Rooting filaments, drawn from paratype. Scale bar 5 mm.

Nematocyst	Dimensions	Aboral Oral Gonophore Tentacle Tentacle
Stenotele (i)	Absent	N	A
capsule	18-19 x13-15
shaft	13
Stenotele (ii)	Absent	Absent	A
capsule	15–17 x 14-15
shaft	14
Stenotele (iii)	C	Absent	Absent
capsule	14 -16 x11-14
shaft	12
Stenotele (iv)	A	Absent	R
capsule	12–13 x 8-10
shaft	8-10
Stenotele (v)	Absent	C	Absent
capsule	10-11 x 8-9
shaft	8
Desmonene	7-10 x 6-8	A	A	Absent
Microbasic mastigophore	12-15 x 4-6	A	A	C
Heterotrichous anisorhiza		R	Absent	R
diameter	15-16

Cnidome comprising one category (stenotele) of five size classes and three categories of nematocysts each of one size class (desmoneme, microbasic mastigophore, heterotrichous anisorhiza). Nematocysts, measurements ( μ m) Key to abundance: A = abundant, C = common, N = not common, R = rare Figure 1. Corymorpha rubicincta , fertile hydranth, in situ image, depth 5 m. Aboral, oral tentacles and gonophores with abundant stenoteles. Desmonemes absent from gonophores. The heterotrichous anishorhiza has a very long and spinous thread.